Model must only allow values inside of array for EnsureInclusionOf

lib/shoulda/matchers/active_model/ensure_inclusion_of_matcher.rb

@@ -83,7 +83,7 @@ def matches?(subject)
               disallows_higher_value &&
               allows_maximum_value
           elsif @array
-            if allows_all_values_in_array? && allows_blank_value? && allows_nil_value?
+            if allows_all_values_in_array? && allows_blank_value? && allows_nil_value? && disallows_outside_values?
               true
             else
               @failure_message = "#{@array} doesn't match array in validation"
@@ -138,8 +138,19 @@ def allows_minimum_value
         def allows_maximum_value
           allows_value_of(@maximum, @high_message)
         end
-      end
 
+        def disallows_outside_values?
+          disallows_value_of(value_outside_of_array(@array))
+        end
+
+        def value_outside_of_array(array)
+          not_in_array = array.last.next
+          while array.include?(not_in_array)
+            not_in_array.next!
+          end
+          not_in_array
+        end
+      end
     end
   end
 end

spec/shoulda/active_model/ensure_inclusion_of_matcher_spec.rb

@@ -1,6 +1,16 @@
 require 'spec_helper'
 
 describe Shoulda::Matchers::ActiveModel::EnsureInclusionOfMatcher do
+  context "with no validations" do
+    before do
+      @model = define_model(:example, :attr => :string) do
+      end.new
+    end
+
+    it "should reject an array which does not have a validator defined" do
+      @model.should_not ensure_inclusion_of(:attr).in_array(%w(Yes No))
+    end
+  end
 
   context "an attribute which must be included in a range" do
     before do